Name: Defensive coding in SQL
Rating: 4.9 (4497 reviews)
Author: booyaa

Defensive coding in SQL

Always wrap ON clauses in parens to avoid predicates being deleted accidentally. The following code will scream if you delete the AND clause.

SELECT *
  FROM foo
  LEFT JOIN bar
    ON ((foo.id = bar.id)
        AND (foo.fizz = bar.buzz))

Where as the following won't.

SELECT *
  FROM foo
  LEFT JOIN bar
    ON foo.id = bar.id
        AND foo.fizz = bar.buzz